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Old 02-14-2016, 09:22 PM   #91
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Drafting works on most Formula race bikes too. But no way I would want to stay that close on the highway.
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Old 02-14-2016, 09:23 PM   #92
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Drafting works on most Formula race bikes too. But no way would I want to hang that close on the highway.
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Old 05-26-2018, 11:19 AM   #93
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Year: 1954
Coachwork: wayne
Chassis: old f500- new 2005 f-450
Engine: cummins 12 valve
Rated Cap: 20? five rows of 4?
The intention with short bus

Drag coefficients are calculated a number of ways none of them are exact on paper. Some test methods are better than others. Length comes into play also.

example two buses, one a 24' short bus and one 35' bus. same nose, same body other wise. I would expect the longer bus to have better drag numbers.

The trailing side is most important. Do you see many fish with flat butts? Some whales and dolphins have pretty blunt noses/fronts, but not flat cut off rear ends.

I bought the 1954 wayne because of the rounded tail end. I wish the front window was sloped more, but I am not going to redo that can of worms. I have enough to get done already.

I am trying all I can do setting up the drive train to keep engine rpm low as possible in top gear, and at peak torque in the gear below top gear.

When you put an under tray on a bus that never was designed for one, you can create heat problems for the engine/transmission. In my case, the front radiator/engine/transmission, need enough air to keep cool. When you under tray, you also need a place for the air to get out. smoothly.

The turbulent air is the bigger hurt. Low speed aerodynamics testing is easy with scotch tape, pieces of yarn 8" long and a trip down the road. Place tape in the middle of the yarn and stick it to the bus. Do this where ever you want to see what the air is doing. Best scenario is the yarn blows towards the back of the bus. Worst is when the yarn blows to front of the bus.

After you learn what the air is doing, then you can begin to decide how to shape the air.

If you can under tray front to back I don't think an air dam will do much.

If you can't under tray then put a deep air dam and cut off one inch at a time and then test. Keep the air dam (frontal area) as little as you can and keep full benefits of the air dam.

Disc covers - smoothies - on the rear duals will help.
Short wheel nuts on the fronts will help.

When you have an area of the yarn going all over the place, that is an area to put stuff were aerodynamics will not matter much. Like a CB antenna, Marker lights, door handles, mirrors.

I expect to find trapped air built up under the hood of my 1954. Getting that air out will help cooling engine transmission.

I already know I will use side cameras, do something different about the big turn signals sitting on top of the fenders, under tray, and something to blend the bottom rear air back up to the air flow.

I will probably make side skirts for the rear wheel wells, I have been looking at some of the old buses that have what looks like rear fenders about an inch deep on the sides... I would like to graft those on, with fender skirts. They will look neat painted a contrasting color and the skirts will go better with that look. Kinda like the rear on a Cord 812

One thing I will try is to put a tear drop on the front beam axle. The profile will look a lot like a wing strut if I can do it.
Some sort of taper tail behind rear duals. A fairing behind them will get shredded if a tire fails.....

If you have an inner fender liner for wheels and keep the liner as close as you can to the tire, that will help.

Rib tread tires are better than tires with lugs. Tires with deeper tread are worse ... for aerodynamics, nother whole story bout hydroplaning, or light snow/slush conditions.

Skinny better than wide for aerodynamics. I want to run 225 70 19.5, for less engine rpm, I am going with 245 width. The wider tire also weighs about 25 lbs more, or 150lbs more for all six.

Front radiator buses, an air dam may aid in cooling. The air dam may help to lower the pressures behind the radiator. For that to work, you have to effectively "seal" areas on the front to reduce air flow around the radiator, make the air go through it.

From testing on road cars, I find, at about 35 mph things start to change with air flow, many cowl induction hoods don't seem to do any thing below that point and do what they need to above that point.

Law of diminishing returns. Target the big stuff first. You get to a point where the time, effort, money don't seem to gain much.

NACA ducts are designed to be effective and low drag, They have a very specific profile in order to work well. Coolers, engine oil, engine coolant, transmission coolers, could be all ducted so that they will add energy to forward motion if very well designed. Most of us will never be able to do it. probably not worth effort, because if you get it wrong enough you will over heat stuff that is expensive to repair.

I am pleased to have found this thread. I hope that somebody else finds what I have written, interesting.

william
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Old 05-26-2018, 12:25 PM   #94
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William, it appears as if you have really thought things through on trying to minimize the coefficient of drag for your bus.

The basic problem is a bus is a big brick shape that by design is very un-aerodynamic. Some buses are notably better than others. Your rounded '50's vintage Wayne it going to be much better than the later Wayne Lifeguard bus bodies that were the definition of square box.

I am not sure exactly what you mean when you refer to under tray.

I am going to assume you mean stuff hung under the sides of the bus.

The smoother you can make the side profile the slippery-er the bus will be.

Having all of the bottom of the lower skirt the same depth will help with making the air flow smoother.
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Old 06-03-2018, 11:11 PM   #95
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Join Date: May 2018
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under tray

imagine, if you will the entire bottom of the bus smooth, no axles, drive shafts, exhausts, exposed. The side mirrors add drag. The rear axle housing, shock absorbers all are licked by the air stream, they add drag. So, if I could I would make a horizontal plane as low as the rear axle, front axle to get them out of the air flow. If that would be practical. I am supposing the front axle on my f450 chassis is going to be too low to be practical to smooth over, so I will attempt to put a fairing on it.
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Old 06-04-2018, 10:43 AM   #96
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Have you read this thread:

http://www.skoolie.net/forums/f13/ae...ics-18789.html

In that thread, I posted a link to the "AeroRV". He saw some impressive gains in economy with a boattail. All kinds of good aero stuff at that site if you poke around.
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